The victim who was killed was identified as 38-year-old Tika Justice. Her daughters, ages 16 and 20, survived and are now hospitalized.
The 16-year-old was found with her mother's body, officials said. The 20-year-old was found chest-deep in debris when first responders arrived.
James Feig was the first one at the scene after the three-story home collapsed around 6:50 a.m. Monday in the 1800 block of South Broad Street. He found the 20-year-old calling 911 for help.
"I rode up to it, went back behind the billboard, and there was a lady buried in the rubble," Feig said.
He found the woman trapped from the waist down. He took a picture after attempts to try and free her were unsuccessful.
"She had the phone in her hand; she was talking to dispatch," Feig said.
Feig said they tried to call out to others who were trapped.
"No response. So they either couldn't hear us or were unconscious," Feig said.
But Feig continued to try to help and comfort the woman.
"Soon as I saw the fire truck come up the road I told her, 'Here comes the fire truck, hold on.' It brought tears to my eyes," Feig said.
Hamilton police and other first responders arrived on the scene to what they describe as a full structural collapse. They pulled three residents from the home, including the woman who called 911. She was rescued first.
"She was doing well and that's what you want to see and I was just so happy at that point just to see somebody come out of there," witness Casey Teuchert said.
The last resident could be seen being taken out on a stretcher.
Most residents said they did not hear an explosion, only the collapse itself. Authorities arrived at the scene to shut off gas lines, which is standard procedure for these types of incidents.
The cause of the collapse has not been determined at this time and is under investigation.
Mercer County, NJ 3-story home collapses this morning with at least 3 residents inside. @PSEGNews is on scene to shut off gas as is standard procedure. No word on injuries or cause of collapse yet. @6abc pic.twitter.com/hf0Ka0SjvY— Jeannette Reyes (@6abcJeannette) July 23, 2018